In an acceleration device for an automotive vehicle for controlling a vehicle acceleration condition depending on a stepping stroke amount of an acceleration pedal, which is operated by a vehicle driver, a rotational angle sensor detects a rotational angle of a pedal shaft for the acceleration pedal. A rotational angle of the pedal shaft corresponds to the stepping stroke amount of the acceleration pedal. The acceleration device has a stopper member rotated together with the pedal shaft. A contacting portion of the stopper member is brought into contact with a stopper surface of a supporting body of the acceleration device when the acceleration pedal is in its acceleration fully-closed position, so that the rotation of the pedal shaft is limited at a predetermined rotational angle.
In a known acceleration device, for example, as disclosed in Japanese Patent Publication No. 2004-090755, an elastic member is provided at an inner wall of a supporting body and a contacting portion of a stopper member is brought into contact with the elastic member, which is elastically deformed. The elastic member is provided in order to decrease hammering sound, which is generated when the contacting portion is brought into contact with the supporting body.
In the acceleration device of the above Japanese Patent Publication No. 2004-090755, each of the contacting portion and the elastic member is formed in a flat surface. The contacting portion of the stopper member is in contact with the inner wall of the supporting body when an acceleration pedal is in its fully-closed position. When a position of a center axis of a pedal shaft with respect to a center axis of a bearing for rotatably supporting the pedal shaft is displaced, a virtual straight line connecting a center of the contacting portion and the center axis of the pedal shaft with each other is declined from a virtual straight line of an initial condition of the acceleration device. As a result, a rotational angle of the pedal shaft in an acceleration fully-closed condition becomes different from that in the initial condition, when the position of the center axis of the pedal shaft with respect to the center axis of the bearing for the pedal shaft is displaced. Then, the rotational angle of the pedal shaft detected by a rotational angle sensor, which is detected in the acceleration fully-closed condition, becomes unstable.